WASHINGTON — An Austrian collector has found what may be the oldest globe, dated 1504, to depict the New World, engraved with immaculate detail on two conjoined halves of ostrich eggs.

The globe, about the size of a grapefruit, is labeled in Latin and includes what were considered exotic territories such as Japan, Brazil and Arabia. North America is depicted as a group of scattered islands. The globe’s lone sentence, above the coast of Southeast Asia, is “Hic Sunt Dracones.”

“ ‘Here be dragons,’ a very interesting sentence,” said Thomas Sander, editor of the Portolan, the journal of the Washington Map Society. The journal on Monday published a comprehensive analysis of the globe by collector Stefaan Missinne. “In early maps, you would see images of sea monsters; it was a way to say, ‘There’s bad stuff out there.’ ”

The only other map or globe on which this specific phrase appears is what can arguably be called the egg’s twin: the copper Hunt-Lenox Globe, dated around 1510 and housed by the Rare Book Division of the New York Public Library. Before the egg, the copper globe had been the oldest one known to show the New World. The two contain remarkable similarities.

After comparing the two globes, Missinne concluded that the Hunt-Lenox Globe is a cast of the engraved ostrich egg. Many minute details, such as the lines and contours of the egg’s territories, oceans and script, match those on the well-studied Hunt-Lenox Globe.

The egg’s shape is slightly irregular, while the copper globe is a perfect sphere. Also, the markings around the equator of the egg, where the halves are joined, appear quite muddled.

Missinne argues that the egg has shrunk and warped over time, and he confirmed a loss in shell density by using computed tomography. He also says the halves were cast separately, then joined later with a type of glue that obscured the engraving around the equator.

The egg, whose owner remains anonymous, was purchased in 2012 at the London Map Fair from a dealer who said it had been part of an important European collection for decades, according to Missinne. From there, Missinne, a real-estate project developer originally from Belgium, consulted more than 100 scholars and experts in his yearlong analysis of the globe.

“He’s put about five years of research into one year,” said Sander, who called Missinne’s journey “an incredible detective story.”

Missinne, 53, developed his passion for collecting exotic and rare objects 20 years ago, when he bought his first antique map — an 18th-century copper engraving of northern Germany — without knowing its origins, and went on an investigation to find out more about it.

“From prints and maps you come to globes, and from globes you come to other artifacts including art-chamber objects like this ostrich-egg globe,” he said.

Missinne speculated that the globe could have loose connections to the workshop of Leonardo da Vinci, based on the etching of an Indian Ocean ship similar to one by an artist well-acquainted with Leonardo.

The egg has no name engraved on it, so the maker is unknown. But Sander thinks that someone from Leonardo’s era consolidated knowledge from travelers and made the globe for an Italian noble family.

“In that time period, the ostrich was quite the animal, and it was a big thing for the noble people to have ostriches in their back gardens,” Sander said.

The globe passed from family to family, and after World War II, like many other precious artifacts, it was sold during times of economic crisis, Sander and Missinne said.

Other scholars who have heard about the egg said they find Missinne’s work impressive but want him to provide more details.

“Where this thing comes from needs to be clarified,” said Chet Van Duzer of the John Carter Brown Library in Providence, R.I., an expert in Renaissance cartography. “It is an exciting discovery, no question, but I also think that more testing should be done.”

John Hessler of the Library of Congress said he saw “a couple red flags that popped up” while reading Missinne’s paper. He has heard from a number of sources that Missinne is actually the anonymous owner of the globe, raising a possible conflict of interest, given that Missinne is touting the importance of the discovery.

Missinne declined to comment on whether he owns the globe.

Washington Map Society board member Jeffrey Katz said as long as the scholarly aspect is there, it doesn’t matter whether the author of the study is also the owner of the globe.

And while Hessler said he finds the globe interesting, “the Leonardo connection is pure nonsense.” Duzer agreed that the link is “tenuous in the extreme.”

Hessler described two types of people in the rare-book and map world: those who get overly excited at any new finding and those who are more skeptical. “I tend to be on the skeptical side,” he said.